I can constantly reproduce this crash by simply resizing any window with Compiz enabled and Resize plugin style set to normal (i.e., window content adjusts constantly during resize). The only requirement is to resize by a considerable amount, like doubling the size of the window. Small resizes work, though I get graphical artifacts in the resized area.
I'm using a Sandybridge desktop (i5 2400) with a 1920x1080 single monitor. I can attach the crash file if necessary.

I tried to reproduce using the specific instructions from Mihai and can't. I turned on resize, resize info, and switched default resize mode to normal. I then alt-middle-click resized various windows from big to small and back. Tested on current 8.0 and master.

Bryce and Mihai, I've created a patch that logs some extra information to stderr around the segfault location. I've applied the patch atop 8.0.1 and posted the branch:
git://people.freedesktop.org/~chadversary/mesa.git ; branch 8.0-bug-46739-log1
Could you reproduce the bug with this patch and report back with the log?